24/09/2018 12:24 BST

Small Tortoiseshell Butterfly In 'Dramatic' Decline Despite This Summer's Heatwave

"It's a very worrying trend."

The small tortoiseshell butterfly has seen a 75 per cent decline since the 1970s

The annual Big Butterfly Count has revealed some common species of British butterfly have plummeted in number. 

Once a familiar sight, the small tortoiseshell butterfly saw its worst numbers since the annual count began eight years ago.

Just 23,000 small tortoiseshells were spotted by volunteers during three weeks of summer according to the organisers, Butterfly Conservation. 

It is the latest bad news for a species which has seen a 75 percent decline since the mid 1970s. But this year’s fall in numbers is especially notable because the long warm summer provided perfect conditions for the butterfly.

“In a summer when the weather is typically British and rainy, and the small tortoiseshell performs badly, you could say that’s perhaps not surprising,” said Richard Fox, associate director of recording and research at Butterfly Conservation.

“But in a year when the summer weather is fantastic and most species seem to do well, the small tortoiseshell not doing well is even more dramatic and concerning.

“Lots of our butterflies did well this year,” he added, “but even in a lovely summer, small tortoiseshells are declining – it’s a very worrying trend.”

PA Archive/PA Images
Sir David Attenborough sponsored the event

The small tortoiseshell was not the only butterfly to see a decline this year – red admiral, comma and gatekeeper species are all down on 2017, too.

But the long heatwave did help some species. The large and green-veined whites all saw big increases in numbers compared to last year.

A record 100,000 people took part in the annual Big Butterfly Count, the world’s largest butterfly survey with almost a million butterflies spotted by the public.

The most commonly spotted species in 2018 was the small white, followed by the large white, while the gatekeeper was third.

Big Butterfly Count 2018 results

  1. Small White                      273,650

  2. Large White                      210,665

  3. Gatekeeper                      72,877

  4. Peacock                           54,287

  5. Meadow Brown                51,899

  6. Common Blue                  50,118

  7. Green-veined White         49,515

  8. Speckled Wood                35,294

  9. Red Admiral                      33,508

  10. Small Tortoiseshell            23,210

The count was launched in 2010 by Butterfly Conservation to involve the public in assessing the nation’s wildlife.

The survey is described as “taking the pulse” of nature as butterflies are one of the species that react quickest to changes in the environment, making them good indicators of wider potential shifts.

Veteran broadcaster Sir David Attenborough is president of the charity and sponsors the count.

East Devon District Council faced embarrassment earlier this year when one of its employees misread instructions and chopped down a meadow that was being used to record butterflies